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Beating the Retreat: Discovering the Cost of Defeat for Fighting Monkeys

Troops of monkeys are known to compete over the best food and locations, but when they lose the battle, what is the cost of defeat? New research in the American Journal of Physical Anthropologyexplores the high costs of social competition among groups of primates. The results show defeated primates had to move further and for longer than the victors, using more energy.

By tracking a troop of capuchin monkeys over six months, lead researcher Margaret C. Crofoot from the Smithsonian Tropical Research Institute, Panamá and her colleagues discovered that the primates moved 13% (441 m) further on days they lost interactions compared with days they won interactions. To cover these larger distances, they traveled faster, stopped less frequently, and remained active later in the evening.

These results demonstrate that losing groups pay increased travel costs and suggest that they forage in low-quality areas. They provide some of the first direct evidence that intergroup conflicts have important energetic consequences for members of competitively unsuccessful primate social groups.